1. Field of the Invention
The present invention relates to covers for electrical junction boxes and, more particularly, to a junction box cover which has no metal parts.
2. Description of the Related Art
This application is related to copending U.S. Pat. application, Ser. No. 483,092, filed on Feb. 20, 1990, which is assigned to the same assignee as the present invention. U.S. Pat. application Ser. No. 483,092 describes a poke-through connector assembly for use within an aperture bored in a concrete floor and for providing an electrical receptable in the floor.
Modern, high-rise buildings, such as office buildings, apartment complexes, condominiums and other structures, are typically built from a skeletal steel structure wherein the steel beams forming the structure are interconnected by rivets, bolts or other fasteners. The steel beams that form the floors of the structure are typically covered with corrugated steel plates upon which concrete may be poured. Alternately, reinforced concrete may be poured without the use of the plates. The poured floors provide a resistance to the spread of heat that could ignite materials on an upper floor from a fire on a floor below.
One problem with maintaining the fire rating of the poured concrete floors is the need to establish electrical wiring therebetween. This wiring may be established by boring an aperture through the floor and inserting a floor connector or receptacle therein. The floor receptacles inserted through the concrete floor must be constructed to maintain the fire rating of the poured concrete floor. Some floor receptacles have ignored this problem; see, for example, U.S. Pat. No. 3,646,244. Other receptacles, such as the one described in U.S. Pat. application Ser. No. 483,092, recognize the importance of maintaining the fire rating of a concrete floor.
One important factor in increasing the fire rating of a floor connector is the elimination of metal components in the connector and its associated hardware. The heat conducting ability of most metals makes them an unsatisfactory material for increasing the fire rating of a floor connector. Other junction box covers may be fabricated from a multiplicity of parts making them more expensive and complex to manufacture.